Constant source current regulating system



Oct. 29, 1968 T. B. HORGAN ETAL 3,408,557

CONSTANT SOURCE CURRENT REGULATING SYSTEM Filed Dec. 9, 1965 LEYATTORNEY "connected to the same United States Patent ABSTRACT OF THEDISCLOSURE A regulating circuit provides a shunt circuit path which isso controlled that the total current from the source remains constantregardless of variation in one or more load currents, as well .asvariation in source voltage and load parameters.

This invention relates generally to regulators and it has reference inparticular to regulators for alternating current systems.

Generally stated, it is an object of this invention to provide a simpleand effective regulator particularly for alternating current systems.

More specifically, it is an object of this invention to provide forregulating the current in an alternating current circuit directly, byproviding a variable shunt load which is varied'to prevent currentfluctuations of one load from adversely affecting the performance ofother loads source.

One object of the present invention is to use an alternating currentload signal to control the effective impedance of a shunt circuit inaccordance with the load current so as to vary the current in the shuntcircuit inversely with the load current.

Yet another object of the invention is to provide a backward-lookingregulator which responds to variations in current of one load to rent ofthe one load.

Another object of this invention is to provide a current regulator whichstabilizes the current drawn from a source while permitting peakexcursions of the current supplied to a load.

stant level.

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of the invention as illustrated in the accompanying drawing.

In the drawing, the single figure is a schematic diagram of a regulatingsystem embodying the invention in a preferred form.

Referring to the single figure the numerals 10 and 11 designateconductors for connecting a load device 12 to a source of alternatingcurrent (not shown). The conductors 10 and 11 may be connected toterminals B and B, respectively, from which conductors BA and B'Aconnect the source to the load device 12, while branch conductors 18 and19 are representative of conductors supply- 3,408,557 Patented Oct. 29,1968 ing one or more additional load devices from the same source.

In order to regulate the current drawn from the source, a pair oftransistors Q5 and Q6 are connected between the conductors BA and B'Aadjacent the source to control the current through a regulating resistorR10. The transistors Q5 and Q6 are of the PNP type and are connected inopposed relation, diodes CR8 and CR7 being associated therewith forproviding paths through the transistors Q5 and Q6 on opposite halfcycles of the alternating current source, respectively. The conductivityof the transistors Q5 and Q6 is established by base current suppliedthereto from the positive terminal 30 of a direct current source throughresistor R9, diode CR6, and an adjustable voltage divider R11 which isconnected to ground. This base current is controlled by means of atransistor Q4 which provides a variable shunt between the junction pointof the resistor R9 and the diode CR6 to ground. The conductivity oftransistor Q4 is in turn controlled by a transistor Q3, the base ofwhich is connected to ground through a resistor R7 and also to themidpoint 40 between two transistors Q1 and Q2, which are connectedthrough resistors R5 and R6, respectively, to the positive terminal 30of the direct current bias the terminal 30 through a bias resistor R3and connected to the midpoint 40 by means of a resistor R5. The primarywinding of the transformer T1 is connected by means of a potentiometerR2 to a bridge circuit of rectifier devices CR1CR4, comprising a fullwave bridge rectifier connected across a resistor R1 in series circuitrelation with the conductor BA and the load device 12 so as to produce avoltage responsive to the current drawn by the load device.

It will be seen that the current in the load circuit is sampled by theseries resistor Each of the transistors Q5 and Q6 conducts 0nalternating half cycles through the path provided by the resistor R10and the diodes CR8 and CR7, respectively. Diodes CR9 and CR10 connectedbetween the base and emitters of the transistors Q5 and Q6 providereference bias protection for the transistors and improve the waveformof the shunt load current at the cross-over point. 1. In aregulatingcircuit for a load disposed to be The voltage divider R11provides for balancing the base connected to an alternating currentsource of electrical drives of the transistors Q and Q6 so as to permita energy, much wider disparity between their V than could be meansincluding a bridgecircuit and a transformer for normally tolerated. 5producing a double frequency current responsive A circuit ashereinbefore described has been built and voltage connected in circuitwith the load and source tested for operation with a nominal Z-ampereload on a for producing a voltage proportional to the load 13-v0lt,-60-cycle alternating current line. The maximum current, load variationamounted to 14 amperes. The following variable impedance means connectedin shunt with the component values were utilized: load, and 1 Pants listcircuit means connecting the variable impedance means C 5.6 f, volts.and the voltage producing means to vary the current C 1 4 IBM Type AA.in the variable impedance means inversely with varia- CR (Z IBM Type BLtions in the load current to maintain the total cur- CR IBM Type AA. 15rent from the source constant. CR CR IBM Type AM. 2. A regulatingcircuit in accordance with the combi- CR CR IBM Type AA. nation definedin claim 1 characterized by: Q Q IBM Type 256. the variable impedancemeans comprising an impedance Q IBM Type 099. device connected in shuntwith the load by a pair Q IBM Type 194. of oppositely disposedcontrollable semiconductor Q Q IBM Type 0.22. devices. R 0.5 ohm, 5watts. 3. A regulating circuit in accordance with the combi- R 500 ohmspot. nation defined in claim 1 characterized by: R 200K, /4 watt. thecircuit means connecting the voltage producing R R 16K, A watt. meansand the variable impedance means compris- R 43K, watt. ing a pair ofsemiconductor devices connected in R a 500 ohms, A watt. a push-pullamplifier configuration, and R 1.8K, A watt. a Zener diode connected inshunt relation with a col- R 100 ohms, /4 watt. lector resistor of eachof the semiconductor devices R 17 ohms, watts. 30 to prevent the devicesfrom reaching the saturation R u 2K pot. level. T Stancor PCT-39. 4. Aregulating circuit in accordance with the combi- V H-V) 6 volts. nationof claim 3, characterized by the oppositely disposed semiconductordevices each being shunted by diode means poled in the opposite sense.

5. A regulating circuit in accordance with the combi nation of claim 4characterized by:

the semiconductor devices being transistors, and

A regulating circuit embodying the invention has several advantages overthe prior art. It can regulate the current drawn from an alternatingcurrent circuit directly without requiring a conversion to directcurrent, or the use of mechamcal equlpment' By f i R2 so that h havingadditional diode means connected base-to-emitcurrent drawn from thesource is stabilized at the maxi- 40 ter to provide base bias. mum valueof the load current, regulation is obtained above and below this levelIf desired a value for the 6. A regulatmg circuit in accordance w1th thecombination defined in claim 5 characterized by:

current from the source greater than the maximum load current may beset; but regulation will not occur for the push-pun amphfier Producmg anerror voltage which is averaged by an R-C circuit and excursions abovethis threshold.

a lied to a transistor connected to reduce the base Being cofnpletelytrimslshonzed h dance 13 physlcal Eias of the oppositely disposedsemiconductor dely small; it is also relatively inexpensive compared toother vices of the Variable impedance device to increase methods ofregulanon' In addmon a regulatmg systtm the effective impedance thereofas the load current embodying the invention does not prevent the loaddevice increases from drawing sharp current surges as does the usualcur- References Cited rent limiting circuit. Such surges are oftenessential to the proper operation of circuits and machine timing inUNITED ATE ATENT equipment, and their elimination could n t be t l rate1,487,108 3/1924 Knoop 323-22 X without affecting operation of theequipm 2,816,261 12/1957 Preisig 323-22 X While the invention has beenparticu arly sho n d 2,906,941 9/1959 Brolin 323-22 described withreference to a preferred embodiment there- 2 5 17 10 19 0 Torkildsen323.42 X of, it will be understood by those skilled in the art h t3,088,067 4/1963 Sender 323-42 the foregoing and other changes in formand details may be made therein without departing from the spirit andLEE T. HIX, Primary Examiner.

scope of the invention.

What is claimed is: A. D. PELLINEN, Assistant Exammer.

